Available phosphorus requirement and effect of particle size on phosphorus bioavailability from meat and bone meal for broiler chicks

The objective of this work was to determine the nutritional requirement of available P and the effect of the particle size in the P bioavailability from meat and bone meal for broiler chicks. Two hundred and fifty and 450 Hubbard broiler chicks from 1 to 21 days of age, respectively, were allotted to a completely randomized design, with five (requirement) or nine (bioavailability) treatments, with five replicates and ten birds per experimental unit. The P requirements was determined by means of a basal diet with low P level (.15% available P), supplemented with five levels of P from the dicalcium phosphate. The phosphorus availability was estimated using the relation of the regression coefficient, considering the P from the dicalcium phosphate as 100% available, The estimated nutritional requirement values of available P, determined with the Linear Response Plateau (broken line) ranged from .311% (.104% available P/Mcal ME), for weight gain, to .426% (.142% available P/Mcal ME), for tibia ash (g). The overage P available values for meat and bone meal with large, medium and small particle size were 106.50, 103.56 and 121.94%. respectively.